部分乳腺加速照射近距离治疗技术设备进展

组织间插植是目前随访时间最长的部分乳腺加速照射（ＡＰＢＩ）近距离技术,但其技术实施复杂。球囊设备是简化的ＡＰＢＩ设备。ＭａｍｍｏＳｉｔｅ是第一个ＡＰＢＩ球囊近距离设备,其技术设备简单,很受医生和患者青睐。ＸｏｆｔＡｘｘｅｎｔＥｌｅｃｔｒｏｎｉｃＢｒａｃｈｙｔｈｅｒａｐｙ是改进的基于电子射线源的球囊设备,ＳｅｎｏＲｘＣｏｎｔｕｒａ相对ＭａｍｍｏＳｉｔｅ增加了４个放射源通道,可以更好地根据靶区调整剂量分布。Ｓｔｒｕｔａｄｊｕｓｔｅｄｖｏｌｕｍｅｉｍｐｌａｎｔ和ＣｌｅａｒＰａｔｈ是组织间插植与球囊结合的设备,结合了球囊设备单点插入的优点和组织间插植的剂量学优势。ＡｃｃｕＢｏｏｓｔ是基于乳腺Ｘ线摄影机的无创近距离设备,无需外科插入导管,对瘤腔形状的依赖性小,且无感染风险。     

Dosimetrie an HDR-Afterloading-Geräten mit Ir-192- und Co-60-Strahler: Vergleich verschiedener internationaler Dosimetrieprotokolle

The air kerma rate in air at a reference distance of 1 meter from the source is the recommended quantity for the specification of gamma ray source in brachytherapy. The absorbed dose for the patients is directly proportional to the air kerma rate. Therefore the air kerma rate should be determined before the first use of the source on patients by a medical physicist who is independent from the source manufacturer. The air kerma rate will then be applied in the calculation of the dose delivered to patients.In practice, high dose rate (HDR) Ir-192 afterloading machines are mostly used in brachytherapy treatment. Currently HDR-Co-60 increasingly come into operation, too. The essential advantage of the use of Co-60 sources is its longer half-life compared to Ir-192. In addition, the purchasing and disposal costs are lower. The use of HDR-Co-60- afterloading machines is also quite interesting for developing countries.This work describes the dosimetry at HDR afterloading machines according to the protocols DIN 6809-2 (1993) in relation to the DGMP-Report 13 (2006), IAEA-TECDOC-1274 (2002) and AAPM Report 41 (1993) with the nuclides Ir-192 and Co-60. We have used 3 different measurement methods (with a cylindrical chamber in solid phantom and in free air and with a well chamber) in dependence of each of the protocols.We have shown that the standard deviations of the measured air kerma rate for the Co-60 source are generally larger than those of the Ir-192 source. The measurements with the well chamber had the lowest deviation from the certificate value. In all protocols and methods the deviations stood for both nuclides by a maximum of about 1.2% for Ir-192 and 2.5% for Co-60-sources respectively.     

Dosimetric calculations and VIPAR polymer gel dosimetry close to the microSelectron HDR

In the present study, different dosimetric methods were investigated for their ability to predict the energy dose in the vicinity of the microSelectron HDR 192Ir brachytherapy source. The results of a time-efficient Sievert integral model of proven accuracy in the cm distance range from all 192Ir sources were benchmarked against accurate Monte Carlo derived dosimetric data in the close vicinity of the source. This comparison revealed that the Sievert model is capable of accurate dosimetry even in the mm distance range from the source. The dose rate distributions were compared with results obtained from different versions (v. 13.7 and 14.2.2) of the Plato BPS commercial treatment planning system, for an application following the Paris trial intravascular irradiation protocol. The results of brachytherapy planning system calculations were found reliable at radial distances of clinical relevance. Noticeable errors existed only in the extreme case of dose calculations at 2 mm from the source axis using Plato v. 13.7. Experimental dosimetric data for the intravascular application, as obtained through the VIPAR polymer gel-MRI method, were also evaluated for dose verification purposes. This method allowed with reasonable accuracy the verification of absolute dose distributions for peripheral vessel applications using 192Ir sources.     

A dosimetric intercomparison of brachytherapy facilities in Ireland, Scotland and the North of England.

BACKGROUND AND PURPOSE: A dosimetric intercomparison of brachytherapy remote afterloading units in Ireland, Scotland and the North of England has been carried out involving 9 radiotherapy centres, and sampling 5 HDR and 6 LDR units. MATERIALS AND METHODS: Absolute calibrations have been performed in air on both HDR and LDR sources. The results are expressed in terms of a ratio of local to calibrated value. Frequency distributions were obtained for the multi-source LDR units by individually measuring each source. Using these distributions the effect of non-uniform source strength on the dose rate at Manchester point A was assessed for a typical clinical brachytherapy insertion for carcinoma of the cervix. Both frequency and dose rate distribution curves were modeled using normal statistics and characterised in terms of the mean (mu) and standard deviation (sigma). RESULTS: Evaluation of the HDR units indicated a mean ratio of 1.008 (+/-0.01) while for LDR the mean ratio was 0.997 (+/-0.02). The LDR frequency distributions demonstrated a variation of sigma values extending from 1.4 to 3.0% of mu. It was shown that this non-uniformity in source strength introduced an uncertainty in the treatment planning process of between 0.8 and 1.8% when compared to the assumption of uniform source strength. CONCLUSIONS: The results of this intercomparison indicate dosimetric consistency between centres for both LDR and HDR units. The distribution of LDR source strengths were within expected limits and the resultant dose rate distributions were considered clinically acceptable.     

Optimization of high dose-rate cervix brachytherapy; Part I: Dose distribution

Computer controlled high dose-rate (HDR) brachytherapy afterloading machines are equipped with a single, miniaturized, high activity Ir-192 source that can be rapidly moved in fine increments among several channels. Consequently, by appropriate programming of source dwell positions and times, the dose distribution can be optimized as desired. We have explored the optimization potential of this new technology for two applications: (a) cervix brachytherapy, and (b) transvaginal irradiation. Cervix brachytherapy with a gynecologic ring applicator was simulated by 48 sources of relative activities ranging from 0.17 to 1.00 that were equally distributed between the tandem and the ring. The results confirmed that the optimized distribution of physical doses are superior to those achievable with standard brachytherapy sources and applicators. For example, with five-point optimization, the relative dose-rate in the rectum was only 47% of that in point A; for standard application the dose rate was 47% higher. For transvaginal application 27 sources of relative activities between 0.07-0.79 were placed in the ring and a single source of unit strength in the tandem. Using dose distribution homogeneity as an optimization criterion, the results (+/- 2.5%) were again superior to those obtained for commonly used double ovoid (+/- 15%), linear cylinder (+/- 27%), or a "T" source (31%).     

Development of a TLD mailed system for remote dosimetry audit for (192)Ir HDR and PDR sources.

BACKGROUND AND PURPOSE: In the framework of an ESTRO ESQUIRE project, the BRAPHYQS Physics Network and the EQUAL-ESTRO laboratory have developed a procedure for checking the absorbed dose to water in the vicinity of HDR or PDR sources using a mailed TLD system. The methodology and the materials used in the procedure are based on the existing EQUAL-ESTRO external radiotherapy dose checks. MATERIALS AND METHODS: A phantom for TLD postal dose assurance service, adapted to accept catheters from different HDR afterloaders, has been developed. The phantom consists of three PMMA tubes supporting catheters placed at 120 degrees around a central TLD holder. A study on the use of LiF powder type DTL 937 (Philitech) has been performed in order to establish the TLD calibration in dose-to-water at a given distance from (192)Ir source, as well as to determine all correction factors to convert the TLD reading into absorbed dose to water. The dosimetric audit is based on the comparison between the dose to water measured with the TL dosimeter and the dose calculated by the clinical TPS. Results of the audits are classified in four different levels depending on the ratio of the measured dose to the stated dose. The total uncertainty budget in the measurement of the absorbed dose to water using TLD near an (192)Ir HDR source, including TLD reading, correction factors and TLD calibration coefficient, is determined as 3.27% (1s). RESULTS: To validate the procedures, the external audit was first tested among the members of the BRAPHYQS Network. Since November 2004, the test has been made available for use by all European brachytherapy centres. To date, 11 centres have participated in the checks and the results obtained are very encouraging. Nevertheless, one error detected has shown the usefulness of this audit. CONCLUSION: A method of absorbed dose to water determination in the vicinity of an (192)Ir brachytherapy source was developed for the purpose of a mailed TL dosimetry system. The accuracy of the procedure was determined. This method allows a check of the whole dosimetry chain for this type of brachytherapy afterloading system and can easily be performed by mail to any institution in the European area and elsewhere. Such an external audit can be an efficient QC method complementary to internal quality control as it can reveal some errors which are not observable by other means.     

On the dosimetric accuracy of a Sievert integration model in the proximity of 192Ir HDR sources

PURPOSE: To investigate the efficacy of a Sievert integration model in dosimetry close to 192Ir high-dose-rate brachytherapy sources and validate its accuracy and potential to resolve dosimetric differences between these sources in the cm and mm distance ranges relevant to interstitial and intravascular brachytherapy applications, respectively. METHODS AND MATERIALS: The dosimetric quantities of the generalized Task Group 43 formalism, as well as dose rate profiles in polar and Cartesian coordinates, are calculated, and results are compared to corresponding Monte Carlo data in the literature. RESULTS: Sievert calculations were found in excellent agreement with corresponding Monte Carlo published results. Dose rate polar angle profiles in the cm distance range depended significantly on corresponding anisotropy function data, whereas in the mm distance range, dose rate polar angle profiles are governed by the corresponding geometry function profiles, because anisotropy proved insignificant. Radial dose functions of the sources were found comparable. A simple equation for the calculation of the dose rate constant of the sources within clinically acceptable accuracy is provided. CONCLUSIONS: The particular Sievert model proved capable of resolving dosimetric differences of the sources and provides results within clinical accuracy. Therefore, it constitutes a useful tool for dosimetry in clinical practice and especially in intravascular applications, where there is currently a lack of available dosimetric data.     

192Ir or 125I prostate brachytherapy as a boost to external beam radiotherapy in locally advanced prostatic cancer: a dosimetric point of view.

PURPOSE: This work aims at comparing the dosimetric possibilities of 125I or 192Ir prostate brachytherapy (Bt) as a boost to external beam radiotherapy in the treatment of locally advanced adenocarcinoma. METHODS AND MATERIALS: From 1/1997 to 12/2002, 260 patients were treated. Until 12/2001 a low dose rate (LDR) treatment with 192Ir wires was used, later replaced by a high dose rate (HDR) delivered with an 192Ir stepping source technology. For the present work, we selected 40 patients including the last 20 treated, respectively, by LDR and HDR. The planning CT Scans of all these 40 patients were transferred into the 3D Prowess system for 125I permanent implants design according to the Seattle method. The reference data for dosimetric comparisons were the V100 and the prescribed dose for 192Ir as well as the dose delivered with 125I techniques to the 192Ir V100. We compared V100-150 data as well as doses to the organs at risks (OR) and cold spots (CS). RESULTS: The V100 is 85.3+/-8% for 192Ir LDR and 96+/-2% for HDR techniques (P < 0.0001). In comparison with 125I, the 192Ir LDR mode induces higher hyperdosage volumes inside the CTV but also more CS, while maximal doses to urethra and rectum are, respectively, 17 and 39% less with 125I (P < 0.0001). In comparison with the 192Ir HDR mode, 125I Bt induces higher hyperdosage volumes and slightly more CS deliberately planned around the bladder neck. If delivered doses to urethra are identical, those to the 20% anterior part of the rectum are 33% less with 125I (P < 0,0001). The 125I Bt technique was only possible in 24 out of the 40 patients studied due to pelvic bone arch interference. CONCLUSIONS: At the present time, there is no evident dosimetric superiority of one Bt method when all the criteria are taken into account. However, improving Bt techniques to implant any prostatic size could found the superiority of the 125I or permanent implants. 125I indeed allows large hyperdosage volumes inside the CTV in comparison with 192Ir HDR techniques while lowering doses to OR and minimizing CS.     

Dosimetric characterizations of GZP6 60Co high dose rate brachytherapy sources: application of superimposition method

Background

Dosimetric characteristics of a high dose rate (HDR) GZP6 Co-60 brachytherapy source have been evaluated following American Association of Physicists in MedicineTask Group 43U1 (AAPM TG-43U1) recommendations for their clinical applications.

Materials and methods

MCNP-4C and MCNPX Monte Carlo codes were utilized to calculate dose rate constant, two dimensional (2D) dose distribution, radial dose function and 2D anisotropy function of the source. These parameters of this source are compared with the available data for Ralstron ⁶⁰Co and microSelectron¹⁹²Ir sources. Besides, a superimposition method was developed to extend the obtained results for the GZP6 source No. 3 to other GZP6 sources.

Results

The simulated value for dose rate constant for GZP6 source was 1.104±0.03 cGyh-1U-1. The graphical and tabulated radial dose function and 2D anisotropy function of this source are presented here. The results of these investigations show that the dosimetric parameters of GZP6 source are comparable to those for the Ralstron source. While dose rate constant for the two ⁶⁰Co sources are similar to that for the microSelectron¹⁹²Ir source, there are differences between radial dose function and anisotropy functions. Radial dose function of the ¹⁹²Ir source is less steep than both ⁶⁰Co source models. In addition, the ⁶⁰Co sources are showing more isotropic dose distribution than the ¹⁹²Ir source.

Conclusions

The superimposition method is applicable to produce dose distributions for other source arrangements from the dose distribution of a single source. The calculated dosimetric quantities of this new source can be introduced as input data to the GZP6 treatment planning system (TPS) and to validate the performance of the TPS.     

Audit on source strength determination for HDR and PDR (192)Ir brachytherapy in Sweden.

BACKGROUND AND PURPOSE: To investigate the status of source strength determination in terms of reference air kerma rate (RAKR) for HDR and PDR (192)Ir brachytherapy in Sweden. MATERIALS AND METHODS: RAKR was determined in each of the 14 Swedish afterloaders, using calibrated equipment from the Swedish Secondary Standard Dosimetry Laboratory. RESULTS: Values of RAKR from the external audit, the hospitals and vendors agreed within the uncertainty limits guaranteed by the vendors. CONCLUSIONS: The accuracy in RAKR determination has increased over the last years as a result of increased availability of interpolation standards for HDR (192)Ir and the increased use of robust well-type ion chambers designed for brachytherapy. It is recommended to establish a ratio between the RAKR value from own measurements at the hospital and that of the vendor since such a ratio embeds constant systematic differences due to e.g. varying traceability and therefore has the potential of being less uncertain than the RAKR alone. Traceability to primary standards for HDR (192)Ir sources will in the future significantly decrease the uncertainty in RAKR of (192)Ir brachytherapy.     

Design of a phantom for the quality control of high dose rate 192Ir source used in brachytherapy.

BACKGROUND AND PURPOSE: A new phantom is proposed for measuring the strength of 192Ir high dose rate sources and for verification of the dose calculated by the treatment planning system. The complete formalism and measurement procedure for this phantom is described, as well as the preliminary results obtained in a number of centers around Brazil. MATERIALS AND METHODS: The measurements are performed using powder thermoluminescent dosimeter capsules; the source strength is measured in air and the verification of the dose calculation algorithm in water phantom. The correction factors required to take into account the specificities related to the geometry and the phantom materials have been assessed using the PENELOPE Monte Carlo code and experimental methods. The dedicated phantom, constructed to use as part of a QA program, in this case specifically for high dose rate 192Ir brachytherapy sources, allows simultaneous irradiation of three thermoluminescent dosimeter capsules, requiring only one source stop (dwell positions). RESULTS: The phantom was mailed to seven radiotherapy institutions in Brazil, and the results show its usefulness in verifying the source air kerma and correctness of treatment planning dose calculation in water phantom. CONCLUSIONS: The comparison made between the phantom measurements, the well-type ionization chamber, and source specifications stated by the hospital (most of the times provided by the source manufacturer) agreed within 3% showing the quality in the HDR dose delivery in Brazilian radiotherapy centers.     

(144)Ce as a potential candidate for interstitial and intravascular brachytherapy

PURPOSE: To investigate the suitability of (144)Ce for both interstitial and intravascular brachytherapy applications. METHODS AND MATERIALS: Monte Carlo calculations of radial dose rate distributions in water were performed for (144)Ce in a spring-shaped source and compared with two commonly used interstitial and intravascular sources, (192)Ir and (32)P. The numeric simulations were checked experimentally with a calibrated ionization chamber in a water phantom. Other source characteristics, such as half-life and specific activity, were also compared. RESULTS: For interstitial brachytherapy, (144)Ce presents dosimetric advantages over (192)Ir in terms of higher dose rate at shorter distances and lower irradiation of organs outside the tumor. The source size and shape reduce the anisotropy and the number of dwell positions necessary. The longer half-life of (144)Ce might also be advantageous over (192)Ir. For intravascular brachytherapy, (144)Ce permits the treatment of larger arteries as compared with (32)P, compensates centering errors more effectively, and has a more suitable half-life. The experimental validation showed good agreement (within 10%) with the Monte Carlo simulated dose rate distributions. CONCLUSIONS: There are certain potential advantages of using (144)Ce as a source for both interstitial and intravascular brachytherapy. The basis for this finding is provided by the Monte Carlo radial dose rate comparisons with (192)Ir and (32)P, as well as by such characteristics as half-life and specific activity.     

The irradiation tolerance dose of the proximal vagina.

PURPOSE: The purpose of this investigation was to determine the irradiation tolerance level and complication rates of the proximal vagina to combined external irradiation and low dose rate (LDR) brachytherapy. Also, the mucosal tolerance for fractionated high dose rate (HDR) brachytherapy is further projected based on the biological equivalent dose (BED) of LDR for an acceptable complication rate. MATERIALS AND METHODS: Two hundred seventy-four patients with stages I-IV cervical carcinoma treated with irradiation therapy alone from 1987 to 1997 were retrospectively reviewed for radiation-associated late sequelae of the proximal vagina. All patients received LDR brachytherapy and 95% also received external pelvic irradiation. Follow-up ranged from 15 to 126 months (median, 43 months). The proximal vagina mucosa dose from a single ovoid (single source) or from both ovoids plus the tandem (all sources), together with the external irradiation dose, were used to derive the probability of a complication using the maximum likelihood logistic regression technique. The BED based on the linear-quadratic model was used to compute the corresponding tolerance levels for LDR or HDR brachytherapy. RESULTS: Grades 1 and 2 complications occurred in 10.6% of patients and Grade 3 complications occurred in 3.6%. There were no Grade 4 complications. Complications occurred from 3 to 71 months (median, 7 months) after completion of irradiation, with over 60% occurring in the first year. By logistic regression analysis, both the mucosal dose from a single ovoid or that from all sources, combined with the external irradiation dose, demonstrate a statistically significant fit to the dose response complication curves (both with P=0.016). The single source dose was highly correlated with the all source dose with a cross-correlation coefficient 0.93. The all source dose was approximately 1.4 times the single source dose. Over the LDR brachytherapy dose rate range, the complication rate was relatively stable to small variations of the underlying tumor biological characteristics and the dose rate. The complication rates change approximately an absolute 1% over the range of the alpha-beta ratio (alpha/beta) from 2 to 4 Gy and repair constant (mu) of 0.46/h to 0.60/h. The complication rates increased an absolute 2% over the mucosa dose rate from 1.75 to 3.50 Gy/h. They markedly increased as the dose rate increased above 3.00 Gy/h as in HDR brachytherapy. The projected HDR Grade 3 tolerance varied from 25 Gy for one fraction to 57 Gy for six fractions in addition to 20 Gy external irradiation for nominal 3-5% complication rates. The traditional LDR tolerance dose of 150 Gy was shown to yield nominal 11% and 4% Grades 1 and 2 and Grade 3 sequelae, respectively. CONCLUSIONS: The traditional 150 Gy LDR tolerance dose (single source plus external irradiation) can be relaxed to 175 Gy or equivalently a full mucosal dose of 238 Gy (all sources plus external irradiation) for a nominal 5% Grade 3 complication rate. Higher fractionation is necessary with four to six fractions in HDR therapy for similar rates of sequelae. The mucosal surface dose from a single ovoid, which can be readily computed, remains a convenient tolerance check for treatment planning purposes.     

Optimization in high dose rate brachytherapy for utero-vaginal applications.

BACKGROUND AND PURPOSE: High dose rate (HDR) remote afterloading intracavitary brachytherapy is an effective treatment modality which has some advantages over low dose rate (LDR) techniques for gynaecological cancer. Optimization is one of the possibilities of modern brachytherapy techniques, especially the stepping source technology. The use of the term 'optimization' implies achieving the desired optimum dose distribution by changing some parameters of the treatment. The aim of this study was to theoretically evaluate the optimization possibilities by modifying dwell times and dwell positions of the uterine and vaginal sources. MATERIALS AND METHODS: Working on a virtual utero-vaginal model, the dose distribution variations in the rectum, bladder, mean point B reference points and volume parameters were investigated whilst giving a standard dose to point A in the Manchester system. In this model, the intrauterine tandem consisted of 27 dwell positions for 2.5 mm steps and 14 dwell positions for 5 mm steps. Vaginal colpostats consisted of five dwell positions each for 2.5 mm steps. Using a Nucletron Plato treatment planning system and a Microselectron Ir-192 HDR stepping source unit, the dwell times of the intrauterine (T(u)) and vaginal sources (T(v)) were modified at the ratios of (T(u)/T(v)) 1:1; 1:2; 1:3; 1:4; 1:0.50; 1:0.33; and 1:0.25 for the two different dwell positions, 2.5 and 5 mm steps, of the intrauterine tandem. RESULTS: All evaluated parameters decreased with increasing dwell time ratios of uterine tandem to vaginal colpostats, with the greatest fall in the percentage of rectum reference dose (D(R) %), 23 and 28% for 2.5 and 5 mm dwell positions respectively; in addition, the reference isodose volume decreased by 14 and 17% for 2.5 and 5 mm dwell positions, respectively. All evaluated parameters increased with decreasing dwell time ratios of uterine tandem to vaginal colpostats for both dwell positions. The DR% of 1:1-1:4 (T(u)/T(v)) weightings showed an increase from 40.6 to 58.3 (44%) for 2.5 mm and from 49.2 to 67.5 (37%) for 5 mm dwell positions. The volume was increased by 27 and 37% for 2.5 and 5 mm dwell positions respectively. CONCLUSION: Modern brachytherapy techniques enable the individualization of treatments by optimization procedures in gynaecological brachytherapy applications. By altering the dwell time and position, some important changes in reference points, volume and treatment time can be achieved, whilst maintaining a standard dose to point A.     

Brachytherapy for prostate cancer

This review article aims to overview modern prostate brachytherapy in Japan. Permanent transperineal prostate brachytherapy with I-125 started in September, 2003 in Japan. Brachytherapy has several advantages: the dose is adapted precisely to the tumor shape and size, and the long-lived isotope gives a higher tumor dose with less damage to normal tissue; less-time consuming for patients and staff: long-term results comparable to surgery or external beam series in the USA; and quality of life after brachytherapy also appealing. These advantages have brought about increasing use in Japan as well. Patients with a high probability of organ-confined disease and a low-risk group are appropriately treated with brachytherapy. Brachytherapy candidates with a significant risk of extraprostatic extension should be treated with supplemental external beam radiation therapy. High-dose-rate (HDR) brachytherapy with Ir-192 has preceded seed implants in Japan. HDR has some theoretical advantages. Long-term results of brachytherapy in the USA are comparable with surgery or external beam irradiation so far. We should develop more sophisticated brachytherapy techniques in Japan.     

GZP型60Co源剂量学参数的蒙特卡洛模拟

目的 GZP型⁶⁰Co源高剂量率后装机在临床中已有应用,模拟计算GZP型⁶⁰Co源的剂量学参数。方法 使用EGSnrc蒙特卡洛软件模拟计算已知的BEBIG ⁶⁰Co源(Co0.A86)剂量学参数,与其结果进行对比,验证方法的可行性。对GZP型高剂量率后装机⁶⁰Co源进行建模,用同样方法模拟计算GZP型⁶⁰Co源剂量学参数。结果 对BEBIG⁶⁰Co源,结果与标准数据吻合很好,单位活度空气比释动能强度S_K/A相差0.2%,剂量率常数Λ相差1.0%,径向剂量函数g_L (r)和各向异性函数F (r,θ))曲线吻合。计算得到的GZP型⁶⁰Co源(1、2)号通道的S_K/A和Λ分别是3.011×10^-7cGycm²h^-1Bq^-1和1.118cGyh^-1U^-1, GZP (3)号通道⁶⁰Co源的S_K/A和Λ分别是3.002×10^-7cGycm²h^-1Bq^-1和1.110cGyh^-1U^-1,g_L (r)、F (r,θ)和水模中单位空气比释动能强度的剂量率参照AAPM推荐列出。     

Role of interstitial brachytherapy in the treatment of malignant disease.

Interstitial brachytherapy was first applied using radium needles, with minimum protection of physicians and nurses. Modern techniques involve the use of radionuclide (192)Ir as the source used in computer-controlled remote afterloading machines, which can deliver a high dose rate (HDR). Treatment planning is also undertaken with the use of computers and anatomical cross-section images using CT, ultrasound and MRI. This review presents these modern techniques for tumors of a series of body sites: prostate, head and neck, breast, bladder, brain, and for soft-tissue sarcomas. Low dose rate (LDR) interstitial brachytherapy techniques are also included in this review since in some body sites there is a choice between HDR and LDR.